A Gas Lens Using Unlike, Counter-Flowing Gases

Because of the current interest in gas lenses for possibe use in longdistance laser beam transmission, it seems worthwhile to report on the successful operation of an example of another class of gas lenses. This class of lenses utilizes the difference of specific refractive index of different gases to achieve focusing in a region where there is a variation in relative concentration of different gases. In the device to be described, two gases flow together continuously from opposing tubes into a mixing chamber. The chamber is designed so that t he effective interface where the gases meet is an axially symmetric curved surface, which acts as a lens for light passing down the axis of t he opposing tubes.